I'm also a Chase customer. The problem isn't their security but
rather that their browser detection script doesn't know what
TenFourFox is (despite the fact we advertise with Firefox flags in
the user agent string). No one at Chase seems interested in fixing
The workaround is, as Chris said, to use a user-agent switcher
add-on which makes the browser look like regular Firefox on some
other system. You could also run Chase in a foxbox with "Prevent
the web site from detecting it’s not in a normal browser"
checked, which accomplishes something similar.
You can import one of the prepared user agent lists from here http://techpatterns.com/forums/about304.html (Tools>Default User Agent>Edit User Agents>Import…). Then choose Browsers – Mac>Firefox 45.0 or whatever is the most recent Mac Firefox from the list. You can update/edit this list yourself by going to Tools>Default User Agent>Edit User Agents.